1. Field of the Invention
This invention relates to an apparatus and method for performing a variety of chemical, physical and detecting operations upon a small sample of fluid or fluid-like material.
2. Description of the Prior Art
A description of relevant prior art can be found in my co-pending application Ser. No. 485,548 described above and incorporated by reference.
Several different techniques are popularly known for the analysis of liquid samples. One such device is the continuous flow analyzer of the type produced by the Technicon Corporation. Continuous flow analyzers are well known to those of ordinary skill in the art but have the general disadavantage that they are relatively expensive, bulky in size and nondisposable.
The encapsulation of a reagent in a plastic package is known in the related art. For instance, part of the technique employed by the well known Polaroid Land Camera is to contain a chemical reagent in a plastic pouch and then, by applying roller pressure to it, force the pouch to rupture and spread its content over a sheet of chemically treated paper or between sheets of thin plastic for the purpose of developing the same. Moreover, the desalination of water has been accomplished in emergencies by introducing sea water into a pouch containing a reactive silver containing substance and then squeezing the water out through a filtering medium into the mouth.
Several different types of prefabricated plastic analyzers are described in the following United States patents: Johnson et al, U.S. Pat. No. 3,476,515; Blackburn et al, U.S. Pat. No. 3,497,320; Johnston et al, 3,544,705; Schwartz, U.S. Pat. No. 3,660,033; Agnew et al, U.S. Pat. No. 3,689,224; Goldstein, et al, U.S. Pat. No. 3,697,227; Sharpiro, 3,713,780; and Nighohossian et al, U.S. Pat. No. 3,715,189. The foregoing can be broadly described as being plastic devices containing one or more reaction chambers into which chemical agents or samples may be added. In Johnson et al, the agents are added by rupturing an internal compartment filled with reagent. In Schwartz, the reagent or indicator is located in the reaction chamber itself.
Of special interest is Forestiere, U.S. Pat. No. 3,036,894. Forestiere discloses a "Method of Using Testing Containers" in which a linear chain of small, joined plastic reaction vessels, which are hollow chambers or pouches or bags containing predetermined amounts of reagents are connected together between two pieces of plastic material in strip form. A sample of material is introduced into the top hollow chamber and then squashed through the subsequent chambers in linear order by means of a pair of squeeze rollers. The reagents in the respective hollow chambers are separated one from another by an adhesive barrier "of relatively small area" which will break open when the matters in the chambers are squeezed strongly against it.
The present invention differs from the foregoing prior art in several major respects. Most importantly, the present invention has nothing to do with hollow containers, chambers, pouches or bags such as in the Forestiere patent. The present invention dispenses entirely with containers, chambers, pouches and bags.
In the Forestiere patent reactions are constrained to a pre-set, linear order. That is the sample, after being put in the top bag, is constrained to enter into the following chamber and react with the reagent there and then must enter into the next chamber, and so on in predetermined order. In the present invention the domain of the sample may be conceived as all pathways possible between the various stations. There is no sequence of activities constrained by the geometry of the system.
The Forestere device is generally unsatisfactory in operation as may be seen from the following consideration. Upon crushing or squashing the entrance chamber the sample is squeezed into the first hollow reaction chamber and then reacts with the reagent therein. The entire contents of the first chamber is then crushed into the second pouch to react with the reagent there. The combined contents of the first and second pouches are then squeezed into the third and so on. This may cause the adhesive barriers down the chain to explode open far in advance of the sample being squashed through the chain of chambers and cause the final chamber which is sealed at its end to distend and balloon. The effect may be mitigated by having compressible reagents or having the chambers largely filled with air. To prevent excessive ballooning appropriate venting mechanics would necessarily have to be provided. However, vents would largely mitigate against the processing of noxious materials or virulent bacteria, viruses, etc.
The Forestiere device involves not only chambers in a fixed linear array but also predetermined amounts of reagent in fixed positions with which to react the sample. In the present invention the reagents of interest may be in fixed position and be of predetermined amount but may also be in any position desired, even mobile of themselves and of any desired amount because in the present invention a blister may be not only of the material being tested but a second (or third, or fourth, etc.) blister may be a blister containing the reagent. Such a reagent blister may be pushed around, separated into portions, etc. at the will of the experimenter.
The present invention has an additional advantage over the invention described in my co-pending application Ser. No. 485,548 in that a "blister" may be moved in two dimensions along an activity plane. In the prior art the sample is typically constrained to move in one particular channel or in a plurality of fixed channels. According to the Applicant's invention, the moving blister forms its own channel.